This invention relates generally to the removal of oxygen from air or other dilute source to form a higher concentration of oxygen and is particularly directed to an electrically operated, structurally monolithic oxygen pump for transferring oxygen across a solid electrolyte barrier to form a higher concentration of oxygen.
Present methods of removing oxygen from air or other dilute sources of oxygen involve pumped cryogenic distillation, preferential absorption-desorption under conditions of temperature and/or pressure cycling, or the electrolysis of water. Pumped cryogenic distillation is particularly adapted for supplying large quantities of oxygen and is impractical as an oxygen source where only a limited quantity of oxygen is desired. Preferential absorption-desorption in combination with temperature and/or pressure cycling typically requires an elaborate array of valves and other controls in conjunction with mechanical compressors or pumps and/or heaters and thus represents a complex and somewhat expensive approach to oxygen production. Producing oxygen by the electrolysis of water also results in the production of hydrogen as a by-product. The volatility of the hydrogen thus produced requires extensive safety measures to be adopted rendering this approach more expensive and complex.
Attempts to design a portable, low cost source of oxygen of reduced complexity capable of producing oxygen in relatively high concentration have met with limited success. Performance requirements for a portable oxygen pump are measured in terms of oxygen enrichment, air utilization, cell and array voltage, operating temperature and lifetime, thermal and mechanical shock, startup and shutdown, power cycling, monitoring and control, and geometry or the conformance of the shape of the oxygen source to the particular requirements of a portable application. These performance requirements are typically competing and, in some cases, appear to be mutually exclusive as evidenced by the unsuccessful prior attempts to develop an efficient, portable, low cost and highly reliable source of oxygen capable of producing oxygen in relatively high concentrations. The present invention, however, represents an improvement over prior art efforts in this area in that it affords a monolithic solid electrolyte oxygen pump which is reliable, rugged, easily started up and controlled as well as shut down. The monolithic solid electrolyte oxygen pump of the present invention operates at relatively low temperatures, does not produce hazardous by-products, and is capable of producing oxygen in relatively high concentrations.